Earth-boring tools are used to form boreholes (e.g., wellbores) in subterranean formations. Such earth-boring tools include, for example, drill bits, reamers, mills, etc. For example, a fixed-cutter earth-boring rotary drill bit (often referred to as a “drag” bit) generally includes a plurality of cutting elements secured to a face of a bit body of the drill bit. The cutters are fixed in place when used to cut formation materials. A conventional fixed-cutter earth-boring rotary drill bit includes a bit body having generally radially projecting and longitudinally extending blades. During drilling operations, the drill bit is positioned at the bottom of a well borehole and rotated.
Cutting elements are typically positioned on each of the blades. The cutting elements commonly include a “table” of superabrasive material, such as mutually bound particles of polycrystalline diamond, formed on a supporting substrate of a hard material, such as cemented tungsten carbide. Such cutting elements are often referred to as “polycrystalline diamond compact” (PDC) cutting elements or cutters. The PDC cutting elements may be fixed within cutting element pockets formed in rotationally leading surfaces of each of the blades. Conventionally, a bonding material, such as a braze alloy, may be used to secure the cutting elements to the bit body.
Some earth-boring tools may also include backup cutting elements, bearing elements, or both. Backup cutting elements are conventionally fixed to blades rotationally following leading cutting elements. The backup cutting elements may be located entirely behind associated leading cutting elements or may be laterally exposed beyond a side of a leading cutting element, longitudinally exposed above a leading cutting element, or both. As the leading cutting elements are worn away, the backup cutting elements may be exposed to a greater extent and engage with (e.g., remove by shearing cutting action) an earth formation. Similarly, some bearing elements have been fixed to blades rotationally following leading cutting elements. The bearing elements conventionally are located entirely behind associated leading cutting elements to limit depth-of-cut (DOC) as the bearing elements contact and ride on an underlying earth formation.